Motorola 52nd Street | Site History


1956 – 1963: The Motorola 52nd Street facility was originally constructed in 1956 and in operation until the third quarter of 1999 when Motorola's Communications, Power and Signal Group was split off to become ON Semiconductor. Motorola remains responsible for the remediation effort related to its former operations at the 52nd Street facility. No municipal sewer was available thereby requiring on-site disposal of domestic and industrial waste in underground tanks, leaching fields, drywells, pits, sumps, and surface disposal areas. The types of wastes that were known to be released to the environment at the facility are: solvents, acids, cyanides and sanitary sewage. Solvents, such as trichloroethene (TCE); 1,1,1-trichloroethane (TCA); freon and tetrachloroethene (PCE), were dispensed to various Motorola operations at the facility.

1963 – 1974: The Courtyard was the site of a 5,000-gallon TCA underground storage tank (UST) and a drywell that was approximately 3 feet in diameter and 15 feet deep. The drywell received solvents, mainly TCE and TCA, from 1963 to 1974. The solvents were used at the facility to remove greases, waxes, oils, and Photoresist. Soils and groundwater have been impacted with chlorinated solvents in this area. Additionally, free product solvent has been found in the bedrock at the Courtyard. The Acid Treatment Plant (ATP) was built on a buried waste solvent line suspected of leaking and there were reports of solvent spills in the area.

1974 – 1976: The SWPL area was used extensively as a main staging area of waste chemicals stored in 55-gallon drums that were suspected of leaking.

1982 – 1983: Site discovery occurred in November 1982 when Motorola reported that the 5,000-gallon UST located in the Courtyard area had leaked TCA. From January 1983 to December 1983, Motorola conducted a preliminary investigation which included the installation of 29 monitors. A report was submitted to ADEQ in December 1983. Analytical data indicated soil and groundwater contamination on the facility property, and groundwater contamination continuing to the west of the property. The highest concentrations of contaminants were found in the Courtyard area of the facility. TCE concentrations as high as 1,470,000 parts per billion (ppb) and TCA concentrations as high as 721,000 ppb were found in bedrock. As a result, Motorola entered into a verbal agreement with ADEQ, EPA, Arizona Department of Health Services (ADHS), Arizona Department of Water Resources (ADWR), Salt River Project (SRP) and the cities of Phoenix and Scottsdale (the oversight committee) to characterize the nature and extent of contamination and recommend remedial actions.

1984 – 1987: From October 1984 to June 1987, Motorola completed a Remedial Investigation/Feasibility Study (RI/FS) under the direction of the oversight committee. The RI report summarized the results of source characterization and site investigation. The FS report established remedial objectives (ROs), identified alternative approaches, and evaluated alternative remedies. These draft documents were issued for public comment. Twenty eight potential sources were identified and investigated, such as: past surface discharges, spills, tank and pipe leaks, and discharges to leach fields and drywells. It was determined that the majority of the contamination came from sources in the Courtyard area. A Pilot Treatment Plant (PTP) was constructed in the Courtyard area which included two extraction wells.

1988: A health assessment was completed by Agency for Toxic Substances and Disease Registry (ATSDR) that concluded that the site is unlikely to pose any threats to human health. The report also stated that although on-site and off-site groundwater was contaminated, contaminant levels at the point of extraction were below the levels of concern. In June, Motorola submitted a Remedial Action Plan (RAP) to ADEQ that proposed a remedial alternative, and a public meeting was held in July. In September, ADEQ and EPA issued official approval to implement the recommendations in the draft RAP in a Record of Decision (ROD) for the OU (later designated as OU1) interim remedy. The OU remedy selected consists of the following components: 1) on-site extraction and treatment of groundwater from the Courtyard and 50th Street area, 2) on-site extraction and treatment of vapor phase organic contaminants from soils from the Courtyard, ATP, and SWPL areas, 3) off-site extraction of groundwater designed to contain contaminant migration at the Old Crosscut Canal, 4) on-site treatment of groundwater extracted from off-site wells, and 5) use of all treated groundwater at the Motorola 52nd Street facility. The OU interim remedy was designed to provide overall protection of human health and the environment by containing migration of VOCs and to treat the extracted groundwater to a level which will meet State/Federal standards.

1989: In June, Motorola and ADEQ entered into a Consent Order (CO), lodged with the Arizona Superior Court, requiring Motorola to design and implement an interim groundwater remedy and soil remedies in the OU1 area, and to continue to work on a revised RI/FS Work Plan to define work components leading to a final remedy. The ROs as defined in this CO are to contain and control the migration and level of contaminants in the groundwater through implementation of the work by Motorola. On October 4th , the site was placed on the U.S. EPA’s NPL. Although the site was listed on the NPL, EPA delegated its authority to ADEQ to continue to be the lead agency.

1990: A sump located within a building near the SWPL was identified as another source of contamination, mainly TCA. Initial soil sample results under the sump were as high as 30,000 ppb of TCA. In 1990, ADHS completed a health study entitled: Cancer Incidence and Mortality in an East Phoenix Area Overlying Groundwater Contaminated with Volatile Organic Compounds.  The study found no elevated rates of cancer as compared to the rest of Maricopa County.  

1991 – 1992: ADHS completed a Baseline Risk Assessment that concluded:  The risk of public exposure to groundwater is limited, and therefore causes no imminent health hazard.  EPA completed an ecological risk assessment that concluded: . . . because of [the VOC’s] high volatility and low toxicity relative to freshwater aquatic criteria, exposure of biota to acute or chronic levels of TCA and TCE may not be a concern.  Inorganics (arsenic and lead) would be of most concern to biota because of their exceedance of the fresh water criteria, persistence in the environment, and their potential for bioaccumulation.  In May, a SVE system was constructed in the Courtyard and by June was operational. The SVE was shutdown in March 1993.  Approximately 350 pounds (lbs) of VOCs were removed. In July, the pre-design RI Work Plan was submitted and the full scale groundwater treatment system was placed in operation. The treatment system is considered an interim remedy and the final remedy will be determined after the final OU1 FS and ROD are completed.  The plant treats groundwater by running it through two air strippers connected in series, and is then run through four liquid phase granular activated carbon (GAC) vessels (two parallel sets of two vessels connected in series) for polishing. The treated water is then used by ON Semiconductor for their facility operations. The air emissions are treated by vapor phase GAC. Approximately 95% of the air is recycled through the air strippers and approximately 5% is treated and then released to the atmosphere.

1993 – 1994: ATSDR completed an update to the 1988 Health Assessment. In February, an air sparging (AS)/Soil Vapor Extraction (SVE) pilot program was conducted in two locations within the SWPL area. Approximately 269 lbs of VOCs were removed.  A program was initiated to periodically remove free product solvent from bedrock.

1995: In November, Motorola conducted a soil gas survey consisting of 25 sample locations of the off-site area immediately to the west of the Courtyard and the northern part of the 52nd Street facility. In November, ADEQ completed the first Five Year Review (FYR) of OU1 which determined that the OU1 was operating effectively and meeting the ROs. 

1996: ATSDR completed an update to the 1988 Health Assessment and the 1993 update to the health consultation. In November, the SWPL SVE operations began and continued through April 1997. Approximately 170 lbs of VOCs were removed during the system operation in addition to the approximately 269 lbs that had been removed during the pilot AS/SVE test in February 1993.

2001: In September, ADEQ completed the second FYR of the OU1 remedy.

2002: In response to the FYR, Motorola conducted studies and evaluated the OU1 groundwater treatment remedy in an effort to optimize the system. In November, ADEQ determined that the soil cleanup was complete in the SWPL area. Another health consultation was completed by ATSDR.

2003: In April, Motorola shut down the groundwater treatment system upon discovering cracks in the carbon vessels that serve as air emission controls. The OU1 Effectiveness Report was submitted and ADEQ identified three areas of concern:  1) the stagnation area (downgradient of the off-site capture zone); 2) the area to the north around monitor Well EW-18; and 3) the capture of contaminants in bedrock.  In October, Motorola submitted a Letter of Intent to conduct a FS to evaluate other remedial alternatives and/or optimize the current groundwater treatment system.  Since the groundwater treatment system was off for approximately six months until the air emission controls were replaced, ADEQ required Motorola to conduct an evaluation of capture. Motorola determined that during the time the system was off, contaminated groundwater did not migrate past the capture zone.

2004: In April, Motorola spun off its semiconductor sector into a new company, Freescale Semiconductor, a wholly owned subsidiary of Motorola Inc. Freescale Semiconductor agreed to implement the requirements of the OU1 Consent Decree (CD) and the OU2 Unilateral Order.

2005: In September and December, Freescale submitted a Groundwater Remedial Alternatives Analysis to evaluate other remedial alternatives and potential optimizations to the groundwater treatment system.

2007: Freescale installed three groundwater monitor wells at the Old Cross Cut Canal to better define the groundwater contamination and to evaluate the effectiveness of the treatment system. A FYR addendum report was issued by ADEQ in October, which provides an update on the action items that were listed in the third FYR report dated September 2006.

2008: As of January, the OU1 groundwater treatment (located at 5005 E. McDowell Road) system treated approximately 2.8 billion gallons of groundwater. Since July 1992, 19,285 pounds of contaminants were removed. In December, Freescale installed one bedrock extraction well and two bedrock monitor wells for a bedrock pilot study to collect additional bedrock permeability information and to evaluate bedrock groundwater extraction and its potential to remove mass and enhance the extent of vertical capture in the bedrock aquifer.

2009: Freescale began conducting the bedrock extraction pilot test in September and researching alternative end uses for the treated water. ON Semiconductor announced that the manufacturing operations at the 52nd Street Plant would be terminated.  The treated water from the OU1 Treatment Plant was used by ON Semiconductor in the manufacturing operations. Freescale   evaluated alternative end uses for the treated water. Pending a final decision ADEQ and EPA approved discharge to the City of Phoenix sanitary sewer.  As of December, the treatment plant has treated 1.2 million gallons of groundwater and an estimated 495 pounds of VOCs were recovered. 

2010: Work continued on the Bedrock Study and End Use Alternatives. Community interviews were held for the FYR and to update the CIP. The connection to the City of Phoenix sanitary sewer was completed in December 2010. EPA began Vapor Intrusion investigations.

2011: The FYR was completed in September 2011. The remedy was considered not protective pending vapor intrusion investigation. EPA continues sampling and investigation regarding vapor intrusion.

2012: Freescale submitted a work plan to address data gaps associated with the northern boundary and continues monitoring and maintenance of the groundwater treatment system. Freescale, with EPA oversight, has been conducting a vapor intrusion investigation in the vicinity of the former Motorola facility. Results from soil gas monitoring in the adjacent neighborhoods have indicated the need for indoor air sampling.

2013: Freescale submitted a revised work plan to address data gaps associated with the northern and western boundaries, and within some residential neighborhoods.  Freescale continues monitoring and maintenance of the groundwater treatment system, in addition to sample collection of groundwater and soil vapor.  Indoor air mitigations systems have been installed in several residential homes in the OU1 area.

2014: Freescale installed several monitor wells to further characterize and delineate the extent of TCE in groundwater. Freescale with EPA oversight has continued to perform the vapor intrusion investigation. Indoor air mitigation systems in residential homes continue to be monitored. EPA performed soil gas and indoor air sampling at select locations during February 2014.

2015: NXP submitted a Remedial Investigation Work Plan and seven additional soil vapor monitoring wells were installed in the source areas. In December treated water discharged from the GETS was routed to the Old Crosscut Canal beneficial use.

2016: The Focused (TCE) Mass Reduction Field Scale Pilot Project work plan was prepared. VI investigations conducted at the former 90-acre Motorola campus indicated no VI issues. VI investigation of residential areas was completed and mitigation deployed at 15 residences. Eight new groundwater monitor wells were installed to help fill data gaps in the groundwater monitoring network.

The EPA five year review (FYR) was performed for all the OUs indicated that the COC groundwater plume within OU1 and OU2 was shrinking in size and concentrations were decreasing. The interim remedy at OU1 was deemed protective of human health in the short term. The protectiveness at OU2 was differed until completion of the VI investigation.

2017:  Focused (TCE) Mass Reduction Field Scale Pilot Project Work Plan was approved and implemented. Test wells for the TCE mass reduction pilot project were installed in the Almeria neighborhood.

2018: Work continued with the TCE mass reduction pilot project. Applications of bio-enhancing products and a bio-agent were performed through August. Program monitoring continued through the year with additional injections of bio-enhancing product in December. Preliminary results showed positive in-situ TCE degrading bio-activity. Monitoring for the TCE mass reduction pilot project continued into 2021. Ultimately, results indicated that the induced bio-activity was unsustainable and not suitable for wide-spread implementation (Clear Creek Assoc. 2021. Focused Mass Reduction Field Scale Pilot Project Summary Report. CTS# 413296).

2020:  As part of the RI, a work plan for the installation of four new groundwater monitoring wells (DM633, DM634, DM635 and DM636) northwest of the former Motorola Facility was approved. The purpose of the new wells was to further define the COC plume near the former facility and determine if COCs found at the Almeria neighborhood are linked to the source.

2021: Four new monitoring wells were installed northwest of the former Motorola Facility. Theses well investigate groundwater conditions for a thin saturated layer of alluvium above bedrock and separate zones of the underlying bedrock (Clear Creek Assoc. 2021. Well Installation Report. CTS# 409959). Initial groundwater samples collected from shallow bedrock nearest the former Motorola Facility (DM636) revealed the highest detections of TCE (Clear Creek Assoc. 2021. Supplemental Data Submittal 2021, CTS# 412859). NXP sold a significant portion of the former Motorola Facility which included the former Southwest Parking Lot area.

2022: As part of the RI, the data quality objectives, previously addressed in the 2015 RI work plan, are in review to identify any unresolved data gaps. In addition, NXP submitted a work plan for the removal and replacement of wells at the SWPL area. The final RI is anticipated in 2023.